Touch screen is applied in more and more devices. For example, a touch screen is integrated in the display of a mobile phone, a tablet computer such as an iPad, an all-in-one machine even a desktop computer. These electronic devices may position a touch point accurately with the touch screen. However, as the diversification development of the electronic devices and interactive modes, it is desired that the touch screen may not only position the touch point accurately, but also identify touch by different users. At present, it is needed to provide more effective approach for identifying user-identity by touch.